The present invention generally relates to the field of waste water management and more particularly, is directed to a diverter screen for more efficient handling of solids in combined sewer overflows and storm water runoff.
For many years, municipalities designed their sewer system to accommodate the water run off from storms and heavy rains along with the normal waste water and sewage from homes and commercial establishments. Most of the storm water entered the sewer directly from down spouts on homes and other buildings and from street run off.
Combining storm run off with waste water in this manner was at one time though to be a convenient way of providing a place for the water to be disbursed quickly and prevent large collection pools or puddles from forming. Depending on the adjacent terrain, pools or puddles often would not have a convenient outlet to drain and thus were left to slowly evaporate. The slow process of evaporation leads to stagnation and the attendant health hazzards that stagnate water poses.
While combining storm run off with normal sewage solved many of the storm run off problems, additional urbanization and residential development soon began to burden the sewer system infrastructure, including the waste water treatment plants, of many town and cities. In order to relieve some of the burden, many municipalities began to build separate collection systems for storm water run off. Many other towns and cities simply took steps to prevent storm run off from entering the sewer system altogether.
For many other municipalities, the very high capital cost of building and maintaining a duplicate sewer system for storm run off water makes this approach unavailable. In addition, preventing storm run off from entering the sewer system also has it cost. Thus, many municipalities continued to try to cope with the burdens of a combined storm water run off/waste water system by dealing with the problem at the treatment plant end.
One of the functions of the treatment plant is the removal of solid and floating objects from the waste water before it can be treated and rendered safe for further use or disbursed into a local river, lake or ocean. Storm run off which enters the sewer system greatly increases the number of such objects which are introduced into the system. However, the waste water treatment plant is vulnerable to being deluged with run off water during a major storm.
In order to deal with this problem, current Federal and State regulations allow excess waste water to be diverted around the treatment plant and into local rivers, lakes and oceans during a storm. This is accomplished with the use of regulator or overflow devices in the collection system. More recent regulations require, however, that solid and floating objects of a certain size be removed from the water before it can be allowed to run into the rivers, lakes or oceans.
In order to remove the undesirable solid and floating objects, the prior art teaches the use of separation processing stations outside of the treatment plant for performing a pre-filter of the waste water. The solid objects filtered out as a result of this process must be manually collected and loaded on to transfer trucks for disposal at an appropriate site.
Use of the pre-filter process and collection of the filtered objects adds more cost to the treatment of waste water in terms of added labor and maintenance. Accordingly, there is a need for a more efficient process for removing solid and floating (floatables) objects from waste water.